1. Field of the Invention:
The present invention relates to an apparatus for and a method of packaging product rolls by wrapping protective sheets around the product rolls.
2. Description of the Related Art:
Heretofore, there has been known a roll packaging apparatus for automatically packaging a roll of paper (product roll) with a packaging sheet (protective sheet) (see Japanese Laid-Open Patent Publication No. 2008-087791).
The roll packaging apparatus disclosed in Japanese Laid-Open Patent Publication No. 2008-087791 operates in the following manner. A roll of paper is rotated about its axis to unreel a leading end portion of continuous paper. When the leading end portion of the continuous paper is extended from the roll, the roll of paper is stopped against rotation. Then, a leading end of a packaging sheet having a prescribed length is inserted into the gap between the leading end portion and the roll itself, and adhesive tape is applied to a trailing end of the packaging sheet.
However, the roll packaging apparatus disclosed in Japanese Laid-Open Patent Publication No. 2008-087791 is problematic in that the roll of paper and the packaging sheet cannot be positioned widthwise, and the roll of paper cannot be packaged accurately in a widthwise manner by the packaging sheet. When the leading end of the packaging sheet is inserted into the gap, the packaging sheet is guided by a feeder guide. When the packaging sheet is guided by the feeder guide, the packaging sheet produces a paper dust, which tends to contaminate the roll of paper.
Problems of the roll packaging apparatus disclosed in Japanese Laid-Open Patent Publication No. 2008-087791 will be described more specifically in detail below with reference to FIG. 1 of the publication. Reference characters thereof are given in parentheses.
There are at least two problems that occur when attempts are made to wrap a protective sheet (packaging sheet) accurately in a widthwise manner according to Japanese Laid-Open Patent Publication No. 2008-087791.
The first problem is that, when a packaging sheet (31) reaches a deepest point in a region (B) of a roll (11) of paper, the packaging sheet (31) is positioned widthwise only by a feeder guide (32). Since the packaging sheet (31) is craft paper, for example, if the packaging sheet (31) is curled in a widthwise manner, the substantial width thereof is reduced, thereby increasing the clearance between the packaging sheet (31) and the feeder guide (32). As a result, the leading end of the packaging sheet (31) may be inserted at a position, which is displaced about 1 mm off from the desired position.
The second problem is that, after the packaging sheet (31) has been inserted and cut off by a cutter (34), and then an actuator (23) resumes rotation of the roll (11) of paper to thereby cause the trailing end of the packaging sheet (31), to which an adhesive tape (41) is applied, to move past the feeder roller (33), the accuracy with which the trailing end of the packaging sheet (31) is wound on the roll (11) of paper depends on the degree of cylindricality of the roll (11) of paper, as well as the angle at which the leading end of the packaging sheet (31) is inserted. Since the roll (11) of paper is in the form of a coil of continuous paper (12) wound in layers, the roll (11) of paper may possibly be of a conical or bobbin-like shape. Therefore, even if the leading end of the packaging sheet (31) is inserted accurately, the wound shape of the packaging sheet (31) tends to suffer from accumulated errors when the trailing end thereof ends up being wound on the roll (11) of paper. Even if the angle at which the leading end of the packaging sheet (31) is inserted deviates only 0.1° from the correct angle, it is evident that the trailing end of the packaging sheet (31) suffers from a large error.
If attempts are made to reduce the clearance between the packaging sheet (31) and the feeder guide (32) for the purpose of increasing the accuracy at which the packaging sheet (31) is wound around the roll (11) of paper, then the packaging sheet (31) produces a large quantity of paper dust due to abrasive friction with the feeder guide (32), and such paper dust is liable to stick undesirably to the roll (11) of paper that is to be protected.